One of the primary considerations in designing a structure is that the strength must be sufficiently greater than the stress to assure both safety and reliability. In manufactured parts, the capability of directly mapping out the critical areas where stresses, defects, flaws, cracks, or inclusions occur is extremely important for determining the structural integrity of the part.
Several methods of detecting irregularities in manufactured parts have been developed over the years using high powered optical techniques, ultrasonic surface wave measurement, stress fluorescent penetrant techniques and eddy current inspection analysis. This invention is primarily concerned with detection of irregularities in manufactured parts using eddy current inspection analysis.
A number of different methods and devices for eddy current detection of flaws in electrically conductive parts are already known and are described in particular in U.S. Pat. Nos. 3,737,764, 4,194,149, 3,826,132, 3,475,681 and 4,268,791.
A problem in the prior art has been the display of the eddy current signals in a form which is easily understandable by technicians and users of eddy current inspection methods. The most common form of displaying eddy current results is to use an oscilloscope for displaying eddy current signatures as an eddy current probe traverses the surface of a part. The eddy current probe, upon traversing a flaw generates a signal displayed on the scope representative of some of the characteristics and the type of anomaly detected. A typical display pattern presented on the scope is the two-lobed signal generated by the sensor, as shown in FIG. 1. The display pattern changes with the defect detected in the metallic part. A great deal of previous experience and knowledge of the display pattern and the electrical properties of the material is required for determining the type of flaw represented by this type of display pattern. This invention overcomes previous problems by presenting a three-dimensional image of the surface of a part as an eddy current probe scans the part for identifying defects in the part.